a little more information would be helpful. Is it a PDF that you are reading? In this case the mentioned behaviour is quite normal and will extend to the newest version as well.
Reading an epub file it sometimes takes a second tap if you have used the buttons before. I'm not sure but I guess the touch needs to be reawakened to save energy, but this is no confirmed information.

For the screen there is no calibration-menu because it is capacitive. Calibration is only necessary with resistive touchscreens.

Hi troll05

You guessed right, I was reading djvu files

As the difference capacitive/resistive, I'm absolutely ignorant, I was just testing all the features reported in the owner manual.